Preheat oven to 425 degrees F. Remove outer papery layers from head of garlic and leave innermost layer to keep the head of garlic whole. Remove leaves from beet, if needed. Drizzle with half of the olive oil, 2 tablespoons, and wrap loosely in aluminum foil. Roast in preheated oven until the beet is tender and the garlic starts to turn golden brown, about an hour. Remove from oven. When cool enough to handle, remove cloves from head and peel skin away from beet.

Combine roasted garlic and beet with tahini, lemon juice, remaining olive oil, chickpeas, and salt in the bowl of a food processor. Process until fine. With the food processor running, add a small stream of water until the desired consistency is reached. Process until smooth. Top hummus with gorgozola and walnuts, if desired.